1. AOHS Global Health Unit 1, Lesson 3 Communicable Disease
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2. A communicable disease is passed from one infected person to another
The range of communicable diseases is wide.
Communicable diseases include both the common cold and HIV.

3. The source of communicable diseases can be bacteria, viruses, fungi, or parasites
Most are harmless.
Some cause infections such as strep throat.
Bacterial infections can be treated with antibiotics.
Viruses
Usually make us sick
Cannot survive without a host
Can sometimes be prevented by vaccines or treated with antiviral medications
Do not respond to antibiotics
Name two different infections. Do you think they are caused by bacteria, viruses, fungi, or parasites?

4. The mode of transmission is how the disease moves
What It Means
Direct contact
Contact with an infected person or an infected person’s blood or body fluids
Airborne
Breathing contaminated air
Vectorborne
Spread by an animal or insect, usually the bite of an infected insect
Food-borne and waterborne
Eating contaminated food or drinking contaminated water
Mother to child
Passed from a pregnant woman to her baby during pregnancy, delivery, or through breast milk
Fomite
An object or substance that can transmit disease

5. Some regions are more affected than others by death from communicable disease
# of Deaths
Africa
5,630,313
Americas
671,193
E Mediterranean
1,245,148
Europe
521,107
Southeast Asia
3,684,045
West Pacific
1,052,052
Data from the WHO Global Health Observatory,
Which regions have the most deaths from communicable disease? Why do you think that is?

6. The WHO tracks several important communicable diseases
Influenza
Diarrhoeal diseases, including cholera
HIV/AIDS
Tuberculosis
Malaria

7. Influenza is a viral infection that is easily spread through the air or by direct contact
Seasonal influenza can cause severe illness or death in specific groups of people, like the elderly.
In some cases, a more unusual strain of influenza, like H1N1 or avian flu, can kill a higher percentage of people, even healthy individuals.
The WHO tracks the spread of influenza to make sure we stop any unusual strain before it becomes a pandemic.
How can we prevent or slow down the spread of seasonal influenza?

8. This is what the status of H1N1 looked like early on in the pandemic
This map is included under fair-use guidelines of Title 17, US Code. Copyright © World Health Organization.
Copyright © World Health Organization. All rights reserved.

9. Within a year, H1N1 had spread rapidly across the globe
This map is included under fair-use guidelines of Title 17, US Code. Copyright © World Health Organization.
Copyright © World Health Organization. All rights reserved.

10. Diarrhoeal disease may come from food-borne or waterborne infections or as a result of poor hygiene
Globally, there are about 1.7 billion cases of diahhroeal disease every year.
It is the second leading cause of death in children under 5 years old even though it is preventable and treatable.
Diarrhoea drains the body of water and salts; if diahhroea is left untreated, the patient can die from severe dehydration.
Data from WHO, “Fact Sheet 330: Diarrhoeal Disease,”
Why do you think it is mostly children who die from diahhroeal disease?

11. Diarrhoeal disease occurs in every region, but deaths are far more common in developing countries
# of Deaths
Africa
602,717
Americas
41,602
E Mediterranean
140,422
Europe
24,583
South-East Asia
651,315
West Pacific
36,596
Data from WHO,

12. Vaccines are decreasing diahhroeal death in Bolivia
Rotavirus is a diahhroeal disease that hospitalizes many children in Bolivia.
The country has been actively working to vaccinate children against the disease.
The vaccination program is working. Fewer children are getting severely sick.
Data from GAVI Alliance, “Bolivia’s Successful Rotavirus Vaccine Initiative,”
Image retrieved from August 18, 2013, and reproduced here under the terms of the Creative Commons Attribution 2.0 Generic license ( Image courtesy of Peter van der Sluijs.
The rotavirus vaccine was 70%–76% effective in preventing the disease.

13. Cholera is a waterborne diarrhoeal disease that is particularly dangerous
This bacterium infects the small intestine, causing diahhroea and vomiting. If untreated, cholera can cause death within hours.
The WHO estimates that there are 1.4 to 4.3 million cases of cholera every year worldwide, with 28,000 to 142,000 deaths.
Cholera can be prevented by working to ensure safe drinking water and good sanitation.
Most cases are in Africa and South-East Asia.
Data from:

14. A cholera outbreak in Haiti took many lives
Poor sanitation and drinking water
Infrastructure damage
Major earthquake
The devastating earthquake destroyed much of the capital city
Data from WHO, “Fact Sheet 107: Cholera,”
Image retrieved from on August 29, 2013, and reproduced here under the terms of the Creative Commons Attribution 2.0 Generic license ( Image courtesy of Marco Dormino/The United Nations.
After the earthquake, many people were forced to live in refugee camps. How do you think this contributed to the spread of cholera?

15. HIV/AIDS is transmitted through direct contact
HIV attacks the immune system, so a patient can’t fight off disease.
According to estimates by WHO and UNAIDS:
37 million people were living with HIV/AIDS at the end of 2014.
There were 2 million new infections that same year and 1.2 million AIDS-related deaths.
More than 2/3 of new HIV infections were in sub- Saharan Africa.
Data from WHO,
Do you know specific ways that HIV/AIDS is transmitted?

16. HIV is a problem in every region of the world
Copyright © World Health Organization. All rights reserved.
This map is included under fair-use guidelines of Title 17, US Code. Copyright © World Health Organization. Map available online at
The legend shows 0.5% of the population in the Americas is living with HIV. How does that compare to Africa?

17. Tuberculosis (TB) is transmitted through the air, like the common cold
TB is a bacteria that usually attacks the lungs, causing people to develop a bloody cough and persistent fever that can cause death if untreated.
In 2013, 9 million people were sick with TB, including 550,000 children.
TB can be treated with antibiotics.
Almost all of TB deaths occur in low- and middle- income countries.
TB is the leading killer of people living with HIV.
Data from WHO, “Fact Sheet 104: Tuberculosis,”

18. What is malaria’s mode of transmission?
Malaria is caused by a parasite and is transmitted through the bite of an infected mosquito
Malaria is a life-threatening disease that causes fever, headache, chills, and vomiting.
Although it is both preventable and curable, malaria killed approximately 584,000 people in 2013.
Most deaths were among African children.
Data from WHO, “Fact Sheet 94: Malaria,”
What is malaria’s mode of transmission?

19. Malaria is more common in the Southern Hemisphere and in developing countries
Copyright © World Health Organization. All rights reserved.
This map is included under fair-use guidelines of Title 17, US Code. Copyright © World Health Organization. Map available online at
Which populations are at the highest risk of catching malaria? Why do you think some countries, like the United States, are not at risk?

20. Global action to fight malaria has reduced deaths by more than one third
Insecticide-treated bed nets are called ITNs. They are a form of personal protection that have been shown to reduce malaria illness and death due to malaria.
Image retrieved from on August 30, From President’s Malaria Initiative (PMI).
Data from CDC, “Insecticide-Treated Bed Nets,”
A mother and her child sleep in a mosquito net in Tanzania.
For ITNs to be effective, people need to be taught how to use them properly. What do you think are some of the other challenges of making ITNs an effective preventive measure?

21. Progress is being made to fight communicable diseases
In 2014, 73% of the estimated 1.5 million pregnant women living with HIV received effective drugs to avoid transmission to their children.
The WHO continues to develop new health interventions, such as the rotavirus immunization, to fight diahhroeal disease.
The TB death rate has dropped 45% since 1990.
Malaria mortality rates have fallen by 47% globally since 2000.
Data from WHO, “HIV/AIDS” ( WHO, “Fact Sheet 94: “Malaria” ( and WHO, “Fact File: 10 Facts about Tuberculosis” (